Apple is investigating a melting iPhone 7 Plus that’s the subject of a viral video on Twitter, reports Mashable. The owner of the phone, Brianna Olivas, says her phone exploded and started smoking Wednesday morning. Her boyfriend grabbed his phone and started recording the video, which has garnered 21,340 retweets on Twitter.

So my IPhone 7 plus blew up this morning was not even using it, literally no explanation for this pic.twitter.com/sQ8CJt4Y69

— Bree✨ (@briannaolivas_) February 23, 2017

Olivas tells Mashable her phone wouldn’t turn on Tuesday, so she took it to the Apple Store. After a couple of tests, employees told her the iPhone was fine and it soon began working normally again. She charged the phone near her as she slept that night, and the next morning her boyfriend moved the phone to the dresser. As he went to the bathroom he saw the phone smoking and heard it squealing. It soon caught fire and he “quickly grabbed it and threw it into the restroom,” where it blew up.

Olivas has since turned the phone over to Apple for further testing, with the Cupertino company saying it’ll know more within a week. An Apple spokesperson said the company is in touch with Olivas and is “looking into” the matter.

Photos via Brianna Olivas

Exploding smartphones have garnered increased attention since Samsung’s Galaxy Note 7 was plagued with widespread reports of exploding devices, prompting an “unprecedented” recall of the popular device. Lithium-ion batteries are more prone to malfunctioning and exploding when manufacturers and suppliers don’t take proper care in preparing the batteries for use. For example, Samsung blames the Note 7’s battery problems on a flaw that caused two incompatible parts of the battery came together.